1. Field of the Invention
The invention relates to a hollow turbine blade equipped with an internal cooling system, and is particularly concerned with a blade intended primarily, but not exclusively, for the turbine of an aircraft engine, the blade being provided in one of its internal cavities with arrangements for cooling the outer walls of this part of the blade.
2. Summary of the Prior Art
Industrial and commercial competition leads aircraft engine manufacturers to seek constantly to improve the performance and output of their engines. These parameters may be improved, in particular, by increasing the temperature of the gases at the inlet of the turbine. One of the parts of the turbine most stressed by increasing the input temperature is the guide of the first stage of the turbine. It is therefore imperative to effect proper cooling of the blading constituting the guide. Conventionally, this cooling is effected by internal circulation of cooling air in cavities provided inside the blade.
The published French Patent Application FR-A-2 150 475 discloses a hollow turbine blade in which an insert is mounted to form a central partition held on both sides by ribs protruding from the internal faces of the blade walls. The cooling fluid admitted at one end of the blade follows a spiralling path on both sides of the central partition as a result of the presence of the ribs.
In U.S. Pat. No. 4,312,624 a turbine blade is disclosed in which an inner jacket is placed within the blade to define two compartments. Cooling air is admitted at one end of each of the compartments and leaves through holes provided at the other end of each compartment.
U.S. Pat. No. 4,859,141 discloses another turbine blade which is cooled with the aid of a jacket mounted within the blade cavity.
All the known arrangements mentioned above suffer from the drawback of requiring a delicate assembly of a jacket or partition inside the turbine blade. In addition, these arrangements do not achieve a flow of cooling air inside the turbine blade which enables satisfactory results to be obtained.
To overcome these drawbacks it is an object of the invention to provide a turbine blade equipped with a cooling system which does not complicate significantly the construction of the turbine blade and which leads to an improvement of the efficiency of the cooling produced by the flow of air inside the blade, both with respect to the intrados wall and to the extrados wall of the blade.